1. Field of the Invention
This invention relates to a pipe fitting for connecting together pipes for pressurized fluid, and more particularly to a pipe fitting for rapidly and readily connecting an inlet pipe extending from a gas appliance or the like with a supply line for pressurized fluid such as pressurized gas.
2. Description of the Prior Art
A pipe fitting of thus type which has been conventionally used for this purpose is generally constructed in a manner as shown in FIGS. 3 and 4, wherein FIG. 3 is a vertical sectional view showing the conventional pipe fitting prior to use upon connection to a supply line and FIG. 4 is a vertical sectional view showing the pipe fitting in use after the connection.
More particularly, the conventional pipe fitting generally includes a socket body 10 and a connecting plug 40 connected to the socket body 10. The socket body 10 and connecting plug 40 are adapted to be connected to, for example, an end of a supply line for supplying fluid such as pressurized gas and an end of an inlet pipe extending from a gas appliance or the like, respectively.
The socket body 10 includes a main member 11 formed into a hollow cylindrical shape so as to define an internal passage 12 therein and a fitting member 21 threadedly connected to the main member 11 and likewise formed into a hollow cylindrical shape so as to define a passage 22 therein. The main member 11 is provided therein with an annular valve seat 13 acting also as a packing. More particularly, the valve seat 13 is arranged on a stepped support portion 12a circumferentially formed on an inner wall of main member 11 defining the internal passage 12 on a connection side of the main member 11. The so-arrange valve seat 13 is securely held on the stepped support portion 13a by a connecting portion of the fitting member 21 threadedly fitted in the main member 11 from the connection side of the member 11. Between the main member 11 and the fitting member 21 is interposedly arranged a disc-like on-off valve 31, which is openably seated on the valve seat 13 to carry out selective communication between the passages 12 and 22.
The internal passage 12 of main member 11 is formed on an opening side thereof with a plurality of tapered holding holes 12b in a manner to be spaced from one another at predetermined angular intervals in a circumferential direction of the passage 12, in which balls 14 for engagement are movably fitted. The main member 11 is also provided on an outer periphery thereof with an operating sleeve 15 for connection and disconnection. The operating sleeve 15 is slidably fitted on the main member 11 so as to be slidable in an axial direction of the main member. Between the main member 11 and the sleeve 15 is interposed a coiled spring 16 of a cylindrical shape which serves to constantly urge the sleeve 15 to hold it at its engaged position. The sleeve 15 is formed on an inner periphery thereof with a cam surface 15a which acts to inwardly project a part of each of the balls 14 into the internal passage 12.
The on-off valve 31 includes a valve plate 32 of a disc-like shape press contacted with the valve seat 13, a head 33 provided on a side of the valve plate 32 facing the internal passage 22 of the fitting member 21 and a guide 34 arranged on a side of the valve plate 32 facing the internal passage 12 of the main member 11. The so-constructed on-off valve 31 is normally held at its closed position by an elastic force of a coiled spring 35 of a conical shape interposedly arranged between the head 33 and a stepped support portion 22a formed on a periphery of the internal passage 22 of the fitting member 21. The guide 34 of the on-off valve 31 is formed on an outer periphery thereof with a stepped portion 34a for engagement which is used for operating the on-off valve 31.
The connecting plug 40 is formed into a shape like a hollow cylinder having an outer configuration sufficient to permit the connecting plug 40 to be detachably fitted in the internal passage 12 of the main member 11. The connecting plug 40 includes a connecting member 41 formed therein with a passage 42 and having a cylindrical connecting portion 43 positioned on its connection side. The cylindrical connecting portion 43 is formed on an outer periphery thereof with an annular groove 44, which is adapted to be detachably engaged with the balls 14 when the plug 40 is connected to the socket body 10.
When the conventional pipe fitting constructed as described above is not in use wherein the connecting plug 40 is not connected to the socket body 10, the on-off valve 31 is forcedly pressed against the valve seal 13 due to elastic force of the coiled spring 35, to thereby be held at its closed position shown in FIG. 3. This leads to interruption of communication between the internal passage 12 of the main member 11 and the internal passage 22 of the fitting member 21, during which the on-off valve 31 is applied thereto a pressure of fluid or gas. Concurrently, the sleeve 15 is forced in a left-hand direction in FIG. 3 by elastic force of the coiled spring 16 and kept at its engaged position at which it is engaged with the balls 14 by the spring 16, so that the cam surface 15a projects a part of each of the balls 14 inwardly into the internal passage 12 of the main member 11.
Connection of the connecting plug 40 to the socket body 10 is carried out by thrusting the sleeve 15 to its thrusted position against the coiled spring 16 in a direction of an arrow a in FIG. 3 to release engagement of the balls 14 with the cam surface 15a of the sleeve 15 and then fitting the cylindrical connecting portion 43 of the connecting member 41 in the internal passage 12 of the main member 11 which pushing away the balls 14. This results in a distal end of the cylindrical connecting portion 43 being abutted against the annular groove 34a of the on-off valve 31 to push the on-off valve 31 against the coiled spring 35 and a pressure of gas applied thereto to open it. Then, when the sleeve 15 is released from its thrusted position, it is forced to its engaged position in a direction of an arrow b in FIG. 4 to cause the cam surface 15a to inwardly project the balls 14 to fit the balls in the annular groove 44 of the connecting plug 40, resulting in connection between the socket body 10 and the connecting plug 40 being accomplished as shown in FIG. 4. This leads to communication between the internal passages 22 and 12 to permit pressurized gas to be flowed from the passage 22 to the passage 42.
Disconnection of the connecting plug 40 from the socket body 10 is easily carried out by thrusting the sleeve 15 against the coiled spring 16 to its thrusted position in the direction of the arrow a to disengage the balls 14 from the cam surface 15a and then drawing out the connecting plug 40 from the socket body 10. This causes the on-off valve 31 to be forcedly pressed against the valve seat 13 by the coiled spring 35, to thereby be held at its closed position, resulting in interrupting communication between the internal passages 12 of the main member 11 and the internal passage 22 of the fitting member 21. Then, releasing of the sleeve 15 from its thrusted position causes the sleeve 15 to be pushed to its original or engaged position by the coiled spring 16, so that the cam surface 15a projects the balls 14 inwardly into the internal passage 12.
In the conventional pipe fitting constructed as described above, interruption of communication between the internal passages 12 and 22 is carried out by seating the disc-like on-off valve 31 on the valve seat 13. Unfortunately, this causes the on-off valve 31 to still positioned between the passages 12 and 22 even after both passages are communicated with each other, so that it produces flow resistance in a flow path of pressurized fluid or gas sufficient to prevent smooth flowing of gas in the pipe fitting. Also, the conventional pipe fitting has another disadvantage in that connection of the connecting plug 40 to the socket body 10 requires to forcedly push the on-off valve 31 against elastic force of the coiled spring 35 and a pressure of gas applied thereto, resulting in a large operating force being required for the connection. Such a disadvantage is noteworthy because the pressure is applied to a whole surface of the disc-like on-off valve 31. Further, the connection is carried out by merely fitting the cylindrical connecting portion 43 of the connecting member 41 in the internal passage 12 of the main member 11 without using any sealing means, accordingly, the conventional pipe fitting often causes outward leakage of pressurized fluid through a small gap between the internal passage 12 of the main member 11 and an outer peripheral surface of the cylindrical connecting portion 43 before the distal end of the cylindrical connecting portion 43 is pressedly seated on the valve seat 13 acting as also a packing.